Drier furnace



May 24, 1938. H. c. FRENCH ET AL 2,118,502

DRIER FURNACE Filed Dec. 15. 1934 2 Sheets-Sheet l INVENTOR5 if? ATTORNEY,

May 24, 1938. H. c. FRENCH ET AL I 2,118,502

DRIER FURNACE Filed Dec. 15, 1954 2 Sheets-Sheet 2 Patented May v1938 DRIER FURNACE Henry 0. French and 0. Frentlel, Jr.,

Milwaukee. Wis.

, assignorsggto The Bell 00.,

Wisconsin Milwaukee, Wis" a corporation of Application December 15, 1934, Serial No. 757,680

. 7 Claims. The present invention relates in general to improvements in the art of heating, and relates more specifically to improvements in the construction and operation of furnaces especiallyv adapted for usein conjunction with driers.

Generally defined, an object of the invention is to provide an improved furnace and compact in construction, and which is, moreover, highly eflicient in operation.

It has heretofore been common commercial practice to utilize oil-burning furnaces to supply heat to rotary hay driers and the like, and due to the intense heat created by the oil burners, considerable difliculty has been encountered in preventing the fire-brick arches from burning and thus introducing, a serious fire hazard.

accurately control the temperature of the gases of combustion which were utilized for drying purand various other objections inherent in the prior drier furnaces cooperated with the defects stated, to make the former heating devices very unsatisfactory.

It is a more specific object of the present invention to provide an improved drier furnace of the above-mentioned type, which obviates the defects of the prior devices of this character, and which is extremely durable and effective in operation.

Another specific object of the invention is to provide an improved furnace combustion chain her which is effectively protected against destruction by the heat of combustion, and wherein tempered air is'delivered to the combustion zone.

Still another specific object of the invention is to provide an improved furnace especially adapted to deliver accurately regulated quantities of heated gas at accurately controlled temperatures,

to a hay, forage, or garbage drier or the like.

A further specific object of the invention is to provide improved instrumentalities for controlling the heat ofcombustion created in an oil-burning furnace or the like.

An additional specific object of the invention is to provide a simplicity and of greatdurability, manufactured and operated at minimum cost.

These and other objects and advantages will be apparent from the following detailed description.

A clear conception of an embodiment of the several improved features, and of the mode of constructing and built in accordance therewith, may be had by referring to the drawings accompanying and forming a part of this specification, in which like which is simple With these prior-furnaces, it has also been impossible to I furnace structure of extreme which may be of operating drier furnaces reference characters designate the same or similar parts in the v'arious'views.

Fig. 1 is a side elevation of one of the improved furnaces, showing the same cooperating with a Fig. 4 is a transverse vertical section through the furnace, taken alongthe line H of Fig. 1; Fig. 5 is a fragmentary horizontal section through the fuel inlet side of the furnace, taken along the line 5-5 of Fig. 4; and

Fig. 6 is an enlarged fragmentary side view of a portion of the air inlet control mechanism.

While the invention has been shown herein as being specifically applied to an oil-fixed heating furnace for hay driers or the like, it is not desired to unnecessarily restrict the scope by such specific disclosure since some of the features may obviously be more generally applicable to other types of heating appliances utilizing other types of fuel such as gas.

Referring to the drawings, the improved furnace comprises in general a substantially annular fire-brick wall 8 cooperating with fire-brick end walls 9, Ill to form. a cylindrical combustion chamber II; a structural metal support If for the walls 8, 9, III; a casing I 3 cooperating with the support l2 to form a cooling air duct II which connects with the combustion chamber ll .the portion ofthe wall 8 adjoining the passage l5 and duct I! may be constructed of other refractory material. The end wall '9 nearest the injection nozzles iii may be provided with a central sight opening I8, while the opposite end wall. It has a relatively large gas outlet flue i9 communicating centrally with the chamber Ii, I

and both of the end walls 9, l0 may be provided with insulating jackets 20, as shown in' Figs. 3 and 5, which may either be filled with insulating material or left open to the duct i4.

The gas outlet flue l9 has a tempering air inlet control valve 2] associated therewith, and

also has a comminuted hay supply hopper 22 -near the gas delivery end thereof, as shown Figs. 1, 2, and 3. The hopper .22 communicates with a distributing and cut-oi! rotor 23 which has flexible blade portions 24 for preventing breakage of the blades or choking of the inlet in case obstructive material is admitted from the hopper 22. An inclined spout "communicates with the rotor chamber of the supply hopper 22 and is directed toward the delivery end of the flue |9. This delivery end of the flue I! is in open communication with the central portion of a rotary drier drum 26 revolvably supported upon rollers 21, and the joint between the ends of the flue i9 and drum 26 is sealed by a flexible plate 28 and packing 20. v

The cooling air duct it formed by the outer casing l3 and surrounding the wall 8 is provided with an air inlet 3|! at the side of the furnace, said inlet 30 having a series of inlet openings ll controllable in eflective area, by means of a slide 22, as clearly shown in Figs. 1, 4, and 6. The air inlet 20 also has one or more sight openings 33 extending directly into the combustion chamber and'the air flowing from the inlet 3| through the peripheral duct l4 effectively cools the wall 8 while at the same time absorbing heat so as to effect pre-heating. The pre-heated air delivered into the lower portion of the combustion chamber II in a tangential direction is intimately mixed with the fuel delivered from the nozzles l6 and produces a whirling, highly combustible mixture, which is ignited and advances helically toward the outlet flue II. By admitting the air supply at the lower portion of the chamber beneath the oil injecting nozzles, the lower portion of the fuel inlet end of the wall 8 is protected against undesirable oil deposits, and thorough mixing of the atomized oil and pre-heated air is insured.

The fuel. injection nozzles it, four in number, are controllable independently of each other in order to provide a highly flexible fuel supply reg; ulating system. This, combined with the air control afforded by the slide 32, permits accurate control of the combustion and of the combustion gas temperatures. The auxiliary air supply valve 2| permits further control of the temperature and volume of the drying gases, thereby providing highly effective and convenientLv manipulable control means for the furnace. may be removably and adiustably supported on a bracket 34 secured to the side of the furnace near the manipulating handles for the slide 32, so that one attendant may conveniently operate these control elements, as well as the valve 2|, and the cooling of the outer casing by the air in the duct I, as well as the insulating jackets 20, prevents excessive or dangerous heating of the exposed surfaces of the furnace assemblage.

During normal operation of the improved furnaoe, the nozzles it are adjusted so as to admit any desired quantities of fuel such as oil, and the slide I2 is set to admit sufllcient air to properly support combustion of the fuel. Since the conditions within the combustion chamber H are ascertainable through the openings ll, :3,

the operation of the furnace may be thus readily controlled. The coldair admitted from the inlet passage 2| to the innular duct lleifectively cools the entire wall I of the furnace and becomes pre heated before being delivered through the tangential passage I! into the combustion chamber l I. fire burning mixture of fuel and air advances through the chamber I in the form' of a swirling vortex, as indicated by the dot-and-dash line in l 'ig.8,andasthegasesofcombustion entertheo'utletfluel8, complete combustion has taken The nozzles i6 place. The highly'heated gases of combustion passing throughthe flue I! may be tempered by the addition of air past the valve 2|, and are subsequently intimately mixed with the commi'nuted material delivered into the advancing stream by the feed rotor 23 and spout 25. The mixture of hot 'gas and comminuted material subsequently passes through the drier 26 for flnal treatment.

From the foregoing description, itwill be apparent that the present invention provides an extremely simple but highly efllcient furnace for delivering heated gases of combustion to a drier or the like. The furnace walls, which are subjected to the greatest heat, are effectively protected against destruction by over-heating, and the air which is thus'utilized to cool the furnace walls is simultaneously pre-heated before admission thereof to the combustion chamber. The quantity of gases of combustion, as well as the temperature thereof, may be conveniently regulated by adjustmentof the fuel supply nozzles I6 and of the air inlet control slide" and auxiliary valve 2|, thereby not only insuring complete combustion of the fuel, but also providing a simple control for the heat delivered to the drier. The furnace is especially applicable to a drier of the rotary type since it can be conveniently positioned so as to cooperate with-such a drier and with the mechanism for feeding the material thereto. While the end walls 9, II have been shown as being jacketed with insulating jackets 20, these jackets may be left open so as to effect additional cooling of the end walls by the entering air which supports combustion. The improved furnace has proven highly effective and unusually durable in commercial operation and can be manufactured and sold at relatively moderate cost.

It is to be noted, that the air admitted to the combustion chamber through the tangential inlet li, may be utilized for'the dual purpose of supporting combustion within the chamber II and of tempering the flnal gases of combustion. The control valve 2| may if desired, be utilized only in. emergency cases, and the temperature of the flnal gases may be regulated solely by controlling the quantity of air admitted through the openings 2| to the inlet IS. The combustion chamber must, however, be of sufllcient length to insure complete combustion of the gases before reaching the outlet flue ll, and such complete combustion within a relatively short chamber II, is obtained by the furnace horizontally rather than vertically. While this horizontal disposition of the furnace would normally be objectionable due to the fact that the upper conflning wall is subjected to intense heat, the improved cooling arrangement overcomes this objection and protects these heated walls against undesirably rapid deterioration.

It should be understood that it is not desired to limit the present invention to the exact details of construction andto the precise mode of operation herein shown .anddescribed, for various modifications within the scope oi the claims may occur to persons skilled in the art.

- What is claimed as the invention is:

1. In a furnace, a wall forming a; substantially cylindrical combustion chamber having a restricted gas outlet at one end thereof, nozzle means for injecting variable quantities of fuel only into the end of said chamber remote from said outlet and in a tangential direction, means forming an annular lmobstructed conduit for of said wall, and means for varying the effective entire length of said chamber, said conduit having an outlet end formed to inject said air tangentially into said chamber only adjacent the place of fuel injection so as to produce a vortex of gas traveling toward said outlet and the inlet end of said conduit having a series of air supply openings extending throughout the length of said wall, and a slide for controlling the effective area of said air supply openings.

2. In a furnace, a-wall forming an-elongated combustion chamber circular in cross section and having a restricted central outlet at ne end thereof, nozzle means for injecting fuel into said chamber only remote from said outlet and in a tangential direction, means forming an annular unobstructed conduit for conducting air around said wall, said conduit having its outlet end formed to inject said air into said chamber only adjacent the place of fuel injection and the inlet end of said conducting means having a series of air supply openings extending through-' out the length of said wall, and adjustable means for varying the effective area of said air supply openings.

3. In a furnace, a wall forming a substantially horizontal combustion chamber circular in vertical cross sect on and having an axial restricted central outlet at one end thereof, nozzle means for injecting fuel into said chamber only remote from said outlet and in a single tangential direction above the chamber bottom, means forming a single unobstructed annular conduit for conducting air aroundthe exterior of said wall, said conduit having its outlet end formed to inject said air tangentially into said chamber around the admitted fuel and the'inlet end of said conduit having a series of air admission openings extending horizontally along the exterior of said wall, and means for varying the effective area of said air admission openings.

4. In a furnace, a substantially horizontal annular wall forming a combustion chamber circular in vertical cross section and having a hot gas outlet at one end thereof, nozzle means for injecting fuel into said chamber only remote from said outlet and only in a single tangential di-- rection considerably-above the chamber bottom, means forming an annular unobstructed conduit for conducting air around the exterior of said Wall, said conduit having its outlet end formed to inject said air tangentially into said chamber only beneath the point'of fuel admission and the inlet end of saidconduit having air admission openings extending in series along the exterior area of said air admission openings.

5. In a furnace, an annular wall forming a substantially horizontal combustion chamber circular in vertical cross section and having an; axial restricted hot gas outlet at one end thereof, nozzles for injecting fuel into the opposite end of said chamber only considerably above the chamber bottom and in a single tangential direction, an outer casing forming an annular unobstructed air conducting conduit in contact with said wall and extending around and along the latter, the air delivery end of said conduit being directed tangentially into said chamber only beneath said nozzles and the inlet end of said conduit being provided with a series of fresh air admission openings, and means for simultaneopenings.

6. In a furnace, an annular wall forming a horizontal cylindrical combustion chamber having a restricted axial outlet for hot gases of combustiori at one end thereof, a series of nozzles for injecting fuel tangentially into said chamber only near its opposite end and some distance above the chamber bottom, an outer casing form'- ing a single annular air conducting conduit extending around and in contact with said wall and having a delivery end directed tangentially into said chamber only directly below said nozzles, the inlet end of said conduit being provided with a series of fresh air admission openings, and adjustable means for simultaneously varying the quantity of fresh air admitted through all of said openings. I

7. In a furnace, an annular wall forming a horizontal cylindrical combustion chamber having a restricted axial outlet for hot gases of combustion at one end thereof, a series of fuel injection nozzles directed tangentially of said chamber and located only near itsopposite end and above the lowermost portion of the chamber,

means forming a single unobstructed annular air 

